Aisin Transmissions in Jeeps and Rams: AW-4, AS68RC, AS69RC, AS66RC
Since 2007, the Dodge Ram (or Ram truck) has had optional Aisin AW (Aisin-Warner) transmissions. The relationship with Jeep for automatic transmissions goes back much further, to the 1987 Cherokee and Comanche, which used the AW-4 automatic (whose creation was reportedly dominated by Borg-Warner). Indeed, Jeep started using Aisin (not Aisin AW) manual transmissions in 1984, with the Cherokee four and five speeds.
Aisin Seiki is a Japanese corporation founded in 1949 which goes far beyond automotive; around one third of the company is owned by Toyota, but the customer base also includes companies such as Volvo, Ford, and Hyundai. Aisin Seiki is the maker of the AS68RC and AS69RC Ram automatic transmissions.
|Reverse||3.00 or 2.21||3.54||3.54||4.445|
* “2 prime” normally unused.
Aisin AW was a joint venture between Borg-Warner and Aisin Seiki, created in 1969. Borg-Warner, a long-time supplier to AMC and Chrysler, left the joint venture in 1987, selling its share to Toyota, which now owns around 52% of Aisin AW. The joint venture has a technical center in Europe, which does research, rebuilding, and manufacturing.
Aisin AW is the largest producer of automatic transmissions in the world, thanks partly to its massive Toyota business.
Dodge and Ram trucks: AS68RC, AS69RC, AS66RC
The Ram started using the Aisin Seiki six-speed AS68RC automatic transmission in 2007, as an option on all of its diesel-powered chassis cab trucks; the transmission was rated at 750 lb-ft of input torque capacity.
The commercial-grade six-speed automatic was electronically controlled, with advanced electro-hydraulic clutch-to-clutch control and close gear ratios (albeit with a wider range than the Chrysler six-speed) and both static and mobile power takeoff (PTO) capability. The transmissions have three planetary gear-sets, with one overrunning clutch.
Aisin markets this transmission for light duty trucks and buses, and promotes its reduced number of parts compared with their four-speed automatic, a more compact design, and “neutral control,” which reduces engine load at idle to enhance gas mileage.
Starting in 2011, the Aisin torque converter locked up in PTO mode for fuel economy and speed control while using aerial lifts and air compressors; customers also gained the ability to program a precise engine RPM that is activated immediately when the PTO is engaged. The transmission was covered by a 3-year, 180,000 mile warranty.
In 2013, Ram switched to the more robust AS69RC automatic, which also had some control changes for greater durability, and extended availability to the Ram 3500 pickup; Ram also claimed a 1% gain in transmission efficiency, with better driveability. Once again, the Aisin transmission was only available with diesel engines (though it was now standard on some high performance diesels); Ram introduced a dual transmission cooler setup at the same time, along with a transmission fluid heating system. The AS69RC has three planetary gear-sets, one over-running clutch, and full electronic control over shifting and the torque converter clutch.
Starting in 2014, Ram 4500 and 5500 chassis cabs carried a standard Aisin AS66RC (also optional on Ram 3500). This transmission provided an optional 45 hp and 250 lb-ft of torque through a power takeoff (PTO) on either the right or left side of the cab; the computer uses cylinder deactivation on the Hemi while in PTO mode, saving fuel. The design of the AS66RC seems to be similar to the AS69RC; gear ratios are identical. In the chassis cabs, axle ratios were 4.44 (Ram 3500, 4500) or 4.88 (Ram 4500, 5500).
The AW-4 (Aisin-Warner four-speed) automatic transmission was used in Jeep Cherokees and Comanches from 1987 to 2001, and on the first six-cylinder Grand Cherokees. This transmission requires Dexron fluid, while the 42RE (which replaced the AW-4 on Grand Cherokee midway in the 1993 model year) needs ATF+4. (It was mainly used on six-cylinder Cherokees and Comanches, but reportedly a few were used with the 2.5 liter four-cylinder, with a different torque converter and bell housing.)
Rear wheel drive and 4x4 versions of this transmission were not interchangeable.
The transmission was light to medium duty, and is reputed to run hot, but it provided four speeds at a time when many companies were still stuck on three; it was also fully electronically controlled, again relatively early for that technology, with a lockup torque converter. At launch, it used a reed-switch output speed sensor and 21-spline output shaft, moving to 23 splines midyear in 1990 when the high-output 4.0 engine debuted (on 4x4s, that is; the rear-drive version always used 27 splines). In 1995, the rear-drive wiring connector changed; for both, the 4x4 connector changed in 1997. In 1998, the output speed sensor was changed (for more precision and better durability), and an input speed sensor was added.
|Solenoid 1||Solenoid 2|
Gearing was similar to the Chrysler 42LE, with a moderately smaller range. Shifts were done via solenoid pack (see table at right). A third solenoid locked the torque converter clutch; it was only locked up in third and fourth gear.
Shift firmness could be adjusted. From 1987 to 1991, Jeep added a Power/Comfort switch which dropped the shift points when set to Comfort; after that, they simply went back to the Power shift points. In 1997, Jeep made major changes to the electronics infrastructure and transmission control computer.
The AW-4 transmission was a little longer than 25 inches; the bell housing could be removed, and had a port for the crankshaft position sensor. Ribbing down the rear half of the case added strength.
A mechanic wrote about a problem that causes many shops to replace or rebuild the AW4 automatic transmission: “These have a special type of Park/Neutral safety switch. Starting, reverse lights, and shifting input are all part of this switch function. These are expensive at $250, but it is a switch you can take apart, clean the wipers and contacts, and reassemble.... carefully. With one 298,750 mile 1992 Jeep Cherokee which two shops had said needed a new transmission, this switch was filthy inside; I cleaned it and put it back together, sealed the outer part with RTV to prevent any contamination in future. The Jeep shifts great again. This is the third one we have done and it worked all three times. Be very sure to set up the position of the switch after cleaning with an ohmmeter to make sure it has flow to starter relay in P and N.”